Field of the Invention
The invention relates to a power semiconductor component having a temperature sensor which turns on a controllable switch for controlling the power semiconductor component from a conducting state into a range of higher resistance once a temperature in a semiconductor body of the power semiconductor component attains a critical value.
One such power semiconductor component is described in European Patent No. 0 208 970 B1, corresponding to U.S. Pat. No. 4,937,646, for instance. The temperature sensor therein includes a thyristor, having an anode-to-cathode path which is connected between the gate terminal and the source terminal or cathode terminal of the power semiconductor component. The power semiconductor component may be a power MOSFET or an IGBT.
If the temperature of a power semiconductor component rises above a critical value of 160.degree., for instance, due to a short circuit of the load or an overload, then the temperature sensor short-circuits the control input of the power semiconductor component, turning the power semiconductor component off. Embodiments are also known in which the power semiconductor component is not turned off entirely but rather the gate-to-source voltage is merely reduced enough that the source current (cathode current) is reduced. If the temperature drops below the critical value, then the temperature sensor is reset, and the power semiconductor component again becomes conducting or is controlled to be fully conducting. However, if the short circuit or the overload is not overcome, then the temperature of the power semiconductor component rises again, until the critical temperature is reached. Due to the hysteresis of the temperature sensor, the turn-on temperature is generally only slightly below the turn-off temperature.
With that kind of turn-off behavior of the temperature sensor, a mean housing temperature is established that may be overly high for surface mounted components (SMD), for instance, since the boards can withstand a temperature of no more than 125.degree. C. However, temperature sensors that switch at lower temperatures than 150.degree. to 160.degree. C., are only technologically achievable with effort and expense.